How to check the distance between two game objects?

Hey guys,

So here is my problem, basically I'm trying to create a script that checks if the distance between gameobject A and gameobject B is too far then gameobject A cannot to move to gameobject B and must take a shorter path. I'm not exactly sure on whats the best solution whether I use raycasts to determine the raycast length but they are not rigid bodies. Is there some sort of transform that can check the distance say in a if statement or something?

Thanks for your help.

 

var distance = Vector3.Distance(transformA.position, transformB.position);


if (distance > 3)
{
// too far etc.
}

 

Doesn't seem to work, did you want me to post the code?

 

ya post it

 

Code (csharp):

1. var waypoint: GameObject;
2. var ShuttleSelection: GameObject;
3. static var shuttleMove = false;
4. static var travelSelection = false;
5. var distance = Vector3.Distance(ShuttleSelection.position, waypoint.position);
6.  
7. function Start () {
8.  
9.  
10.  
11. }
12.  
13.  
14.  
15. function Update () {
16.  
17. waypoint = waypointSelection.selectedWaypoint;
18. ShuttleSelection = ShuttleController.SelectedShuttle;
19.  
20. }
21.  
22. function OnGUI() {
23.  
24. if (ShuttleController.moveGUI == true)
25. {
26.  
27. travelSelection = true;
28.  
29. GUI.Box(Rect(1480,750,150,150),"");
30.  
31. if (GUI.Button(Rect(1500,850,100,25),GUIContent ("Travel", "Move along the board"))){
32.  
33.  
34.  
35. if  (waypoint == null)
36. print ("Select a point to travel");
37.  
38. if (shuttleMove == true)
39. print ("Can only move once per turn");
40.  
41. if (distance > 1)
42. print ("too far to travel");
43.  
44. if (shuttleMove == false)
45. ShuttleSelection.transform.position = waypoint.transform.position;
46. ShuttleController.moveGUI = false;
47. shuttleMove = true;
48.  
49.  
50.  
51.  
52.  
53.  
54.  
55. }
56.  
57.  
58. }
59. }

 

put the distance in the update function, the distance is something that needs to be checked each frame, and i don't know if putting the if statement for the distance in the ongui script is a good idea...

 

It's still not working, I'm getting a null reference error but that's only because the waypoint isn't set until it is selected.

NullReferenceException: Object reference not set to an instance of an object
Boo.Lang.Runtime.RuntimeServices.GetDispatcher (System.Object target, System.String cacheKeyName, System.Type[] cacheKeyTypes, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
Boo.Lang.Runtime.RuntimeServices.GetDispatcher (System.Object target, System.Object[] args, System.String cacheKeyName, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
Boo.Lang.Runtime.RuntimeServices.GetProperty (System.Object target, System.String name)
UnityScript.Lang.UnityRuntimeServices.GetProperty (System.Object target, System.String name)
Movement..ctor () (at Assets/Scripts/Movement.js:5)

 

well then, place a conditional statement in the update function that will run the distance check if the condition is met.

 

I still can't get it too work, same error all the time

 

Whty does it return Boo error messages? Are you sure you created the correct script file type and are using the correct syntax?

 

It's all in Javascript with correct syntax, no other errors except the null reference once. I believe it was because one of the gameobjects was not set until it was selected but even when selected it will travel any distance.

I've changed the code a little and moved it back into OnGUI, and this is the error I get now,

NullReferenceException: Object reference not set to an instance of an object
Movement.OnGUI () (at Assets/Scripts/Movement.js:32)

 

Don't do it on OnGUI. And really - you probably don't have to do it in Update unless it absolutely needs to be checked every frame. But in either case, it's rather straightforward.

Code (csharp):

1.  
2. public class SomeScript : MonoBehaviour {
3.  
4.     private float d;
5.     public float AcceptableDistance;
6.     public GameObject Shuttle;
7.     public GameObject Waypoint;
8.  
9.     void Update()
10.     {
11.         if (Shuttle  Waypoint)
12.         {
13.             d = Vector3.Distance(Shuttle.transform.position, Waypoint.transform.position);
14.             if (d <= AcceptableDistance)
15.             {
16.                  // do stuff
17.             }
18.         }
19.     }
20.  
21. }
22.  

 

Am I missing something on "if(Shuttle Waypoint)"?

 

I assume line 11 is meant to be like

if ((Shuttle != null) && (Waypoint != null))

 

Looks like the various forum upgrades over the years ate some of the formatting. I'm guessing I meant

Code (csharp):

1.  
2. if (Shuttle && Waypoint)
3.  

because 8 years ago using the boolean implicit "exists" overload was a cool thing to do. (It isn't, don't do that)